1. Field of Invention
The present invention relates to a solenoid valve. More particularly, the present invention relates to a solenoid valve having an air tap structure.
2. Description of Related Art
A typical solenoid valve having an air tap structure includes an air tap assembly, a housing, a coil rack, a core member, a plunger, a base, a spring, and two copper contacts. The solenoid valve having an air tap structure has a central tube in the top of the air tap assembly and a lateral tube in the lateral portion of the air tap assembly. Application of an electric current results in inducing a magnetic field such that the core member is attracted the base, thereby resulting in the core member moving downward. Hence, the plunger also moves downward and thus the openings of the central tube and the lateral tube are communicated with each other. When the electric current is turned off, the core member together with the plunger move upward as a result of the spring exerting an upward force on the core member, and as a consequence, the openings of the central tube and the lateral tube are no longer communicated with each other.
One disadvantage of such a configuration is that the plunger can deviate from the central axis of the solenoid valve because the plunger blocks laterally the opening of the lateral tube and the resulting lateral pressure directly contacts the plunger.
Therefore, there is a need to develop a solenoid valve having an air tap structure that is capable of avoiding the foregoing disadvantages.